title: Identification of ferrous-ferric Fe3O4 nanoparticles in recombinant human ferritin cages.
abstract: Recombinant ferritin is an excellent template for the synthesis of magnetic nanoparticles. This paper describes carefully performed experiments both to identify ironoxides within nanoparticles and to measure the number of iron atoms in the cores of recombinant human H-chain ferritin (HFn), based on spectroscopy techniques. Using electron energy-loss spectroscopy (EELS) analysis, magnetite (Fe3O4) has been unequivocally identified as the ironoxide formed within HFn cores under special preparation conditions. Atom counting analysis by EELS and high-angle annular dark-field imaging further allowed the correlation of the particle sizes to the real Fe atom numbers in a quantitative manner. These results help clarify some structural confusion between magnetite and maghemite (γ-Fe2O3), and also provide standard data for the number of Fe atoms within Fe3O4 particles of a given size, whose use is not limited to cases of magnetite synthesized in the cores of recombinant human ferritin.
authors.affiliation: Laboratoire de Physiques des Solides, UMR CNRS 8502, Bât. 510, 91405 Orsay, France.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Walls
authors.forename: Changqian
authors.initials: C
authors.lastname: Cao
authors.forename: Kui
authors.initials: K
authors.lastname: Yu-Zhang
authors.forename: Jinhua
authors.initials: J
authors.lastname: Li
authors.forename: Renchao
authors.initials: R
authors.lastname: Che
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Pan
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry* / Q000378:metabolism; D005293:Ferritins / Q000378:metabolism*; D005296:Ferrous Compounds / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007501:Iron / Q000032:analysis*; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D046590:Spectroscopy, Electron Energy-Loss
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D011994:Recombinant Proteins; C000499:ferric oxide; D005293:Ferritins; D007501:Iron